Certain people should be especially careful about taking folic acid, including those who:
- take anticonvulsant medications. High levels of folic acid can provoke seizures in people on these drugs.
- are being treated for cancer. Folic acid may raise the amounts of certain chemotherapy drugs to potentially dangerous levels while interfering with the effectiveness of other cancer treatments.
- are on antibiotics. Taking folic acid supplements at the same time as certain antibiotics may interfere with the body's absorption of the antibiotics and their effectiveness.
- have a vitamin B12 deficiency. Folic acid may trigger serious symptoms, including potentially permanent nerve damage.